The present invention relates to a power base, or power wheelchair, for disabled persons that is separable for the purpose of transportation. More specifically, the invention relates to a powered wheelchair that has a separating frame that allows the wheelchair to be easily separated into a number of smaller and lighter weight components for transportation without the use of tools. Another aspect of the present invention relates to a powered wheelchair for disabled persons that has a suspension system for the drive wheels that reduces the amount of fore and aft rotation of the wheelchair about the drive axis.
One of the options available to physically impaired persons is the powered wheelchair. The powered wheelchair offers increased mobility and convenience to these individuals. Powered wheelchairs are now of three basic types: rear wheel drive, front wheel drive, and mid-wheel drive. The mid-wheel drive chair puts the weight of the individual traveling therein directly over the drive wheels, which offers increased traction. Further, the mid-wheel drive vehicle offers a better turning radius. However, one of the problems encountered by users of the mid-wheel drive vehicle is what some refer to as a "seasick" or motion sickness problem.
In a typical mid-wheel drive wheelchair, the drive wheels are located under the trunk of the user. A pair of swivel type rear wheels is provided, which typically remain in contact with the ground at all times. It is also necessary to provide a pair of front, stabilizing wheels, which extend in front of the drive wheels. These wheels typically do not travel on the ground at all times, but rather are located a set distance from the ground. If a user is going down a hill, or the wheelchair is otherwise tipped forwardly, the front wheels prevent the chair from tipping or rotating forwardly beyond a set point. Many of the prior art mid-wheel drive vehicles are also equipped with a suspension system for the drive wheels. In these prior art suspension systems, the drive wheels are allowed to rotate about an axis that is perpendicular to the direction of travel. This type of suspension, along with the elevated front wheels, allows the chair to rock fore and aft when the drive wheels encounter a bump or other rise or fall in the terrain on which the chair is traveling. This fore and aft rocking motion can cause a person riding in the chair to feel uneasy, or seasick. Moreover, if the person riding in the chair does not have sufficient physical control of his or her upper body, such a motion can cause a person to rock forwardly and out of the chair.
Those using powered wheelchairs encounter the need to transport the wheelchair from one location to another, such as in a van or car. There are, therefore, available powered lift systems that can lift the entire chair into a van or other vehicle. However, these systems are typically expensive and can only be installed on vehicles that are large enough to accommodate the assembled chair. To address this problem, some prior art chairs are designed to allow the seat to be removed therefrom, making the chair slightly more transportable. Other components, such as the batteries, may also be removable. Further, some prior art chairs have been equipped with a folding frame, to lessen the overall footprint of the chair. It has been found, however, that the degree of separation and folding possible with the prior art chairs is less than satisfactory. The current degree of separation possible with prior art chairs results in assemblies that are both bulky and heavy. Compounding the problem is the reduced openings available in many vehicle trunks. While the actual trunk space has not been reduced, the opening available has been decreased on certain vehicles. This decreased opening has made it more difficult to get larger, bulkier items into the trunk.
The main frame of these prior art powered wheelchairs typically supports and has affixed thereto the drive wheels along with at least one other set of wheels. Even with the seat removed, such a frame and wheel assembly is both bulky and heavy, resulting in the problems discussed above. Any further disassembly involves the need for tools, which is both inconvenient and time consuming. This decreases the uses to which the wheelchair can be put, and also decreases the versatility of the wheelchair.
Another problem encountered by powered wheelchair users involves the wheelbase of the wheelchair. The length of the wheelbase of a powered wheelchair determines, in part, the turning radius for the wheelchair. A longer wheelbase having a larger turning radius can be advantageous in certain situations. For example, if the wheelchair will primarily be used outdoors, a longer wheelbase offers better stability in outdoor conditions. On the other had, a shorter wheelbase is more advantageous when the wheelchair will be used primarily indoors, the shorter wheelbase offering a better turning radius and thus increased maneuverability. Purchasers of powered wheelchairs have heretofore selected, at the time of purchase, a wheelchair having the wheelbase best suited for their needs. This requires a wheelchair purchaser to elect either a wheelchair that is best used either indoors or outdoors, but not both.
Yet another problem faced by powered wheelchair users involves the ability to get as close as needed to desks and tables, while still in the wheelchair. On a powered wheelchair, the controls are typically located in line with one of the arm rests of the seat for the wheelchair. This arrangement places the controls in line with the user's arm, as his or her arm is resting on the armrest. This placement has been found to be best in that the user's wrist is not required to be at an uncomfortable angle in order to control the speed and direction of the wheelchair. This placement, however, restricts the wheelchair from being positioned as close to a table or desk as may be desired. This restriction is due to the fact that the controls protrude forwardly of the terminal end of the armrest. Prior art chairs have been equipped with controllers mounted so as to be able to rotate the controller assembly out of the way. This rotation, however, involves the use of a somewhat complicated structure.
Therefore, a powered wheelchair for disabled persons is needed that can reduce the amount of fore and aft rocking motion encountered by a user thereof. Further, a powered wheelchair is needed that can be separated for the purposes of transportation into a number of lighter weight and more manageable components without the use of tools. Further, a powered wheelchair is needed that allows the wheelbase thereof to be adjusted, to better accommodate the upcoming use of the wheelchair. A powered wheelchair is also needed that allows the controls to remain positioned in line with the armrest of the seat and that also allows the controls to be recessed under the armrest to allow the chair to be better positioned adjacent a table or desk.